You can loop over each row of the DataTable and check the value.
I'm a big fan of using a foreach loop when using IEnumerables. Makes it very simple and clean to look at or process each row
DataTable dtPs = // ... initialize your DataTable
foreach (DataRow dr in dtPs.Rows)
{
if (dr["item_manuf_id"].ToString() == "some value")
{
// do your deed
}
}
Alternatively you can use a PrimaryKey for your DataTable. This helps in various ways, but you often need to define one before you can use it.
An example of using one if at http://msdn.microsoft.com/en-us/library/z24kefs8(v=vs.80).aspx
DataTable workTable = new DataTable("Customers");
// set constraints on the primary key
DataColumn workCol = workTable.Columns.Add("CustID", typeof(Int32));
workCol.AllowDBNull = false;
workCol.Unique = true;
workTable.Columns.Add("CustLName", typeof(String));
workTable.Columns.Add("CustFName", typeof(String));
workTable.Columns.Add("Purchases", typeof(Double));
// set primary key
workTable.PrimaryKey = new DataColumn[] { workTable.Columns["CustID"] };
Once you have a primary key defined and data populated, you can use the Find(...) method to get the rows that match your primary key.
Take a look at http://msdn.microsoft.com/en-us/library/y06xa2h1(v=vs.80).aspx
DataRow drFound = dtPs.Rows.Find("some value");
if (drFound["item_manuf_id"].ToString() == "some value")
{
// do your deed
}
Finally, you can use the Select() method to find data within a DataTable also found at at http://msdn.microsoft.com/en-us/library/y06xa2h1(v=vs.80).aspx.
String sExpression = "item_manuf_id == 'some value'";
DataRow[] drFound;
drFound = dtPs.Select(sExpression);
foreach (DataRow dr in drFound)
{
// do you deed. Each record here was already found to match your criteria
}